Aerobic exercise is a popular form of exercise that improves one's cardiovascular health by reducing blood pressure and providing other benefits to the human body. Aerobic exercise generally involves low intensity physical exertion over a long duration of time. Typically, the human body can adequately supply enough oxygen to meet the body's demands at the intensity levels involved with aerobic exercise. Popular forms of aerobic exercise include running, jogging, swimming, and cycling among others activities. In contrast, anaerobic exercise typically involves high intensity exercises over a short duration of time. Popular forms of anaerobic exercise include strength training and short distance running.
Many choose to perform aerobic exercises indoors, such as in a gym or their home. Often, a user uses an aerobic exercise machine to have an aerobic workout indoors. One type of aerobic exercise machine is a treadmill, which is a machine that has a running deck attached to a support frame. The running deck can support the weight of a person using the machine. The running deck incorporates a tread belt that is driven by a motor. A user can run or walk in place on the tread belt by running or walking at the tread belt's speed. The speed and other operations of the treadmill are generally controlled through a control module that is also attached to the support frame and within a convenient reach of the user. The control module can include a display, buttons for increasing or decreasing a speed of the conveyor belt, controls for adjusting a tilt angle of the running deck, or other controls. Other popular exercise machines that allow a user to perform aerobic exercises indoors include elliptical machines, rowing machines, stepper machines, and stationary bikes to name a few.
One type of treadmill is disclosed in U.S. Pat. No. 4,729,558 issued to Hai P. Kuo. In this reference, an improved running exerciser comprises a base frame having a first shaft and second shaft, a pair of inverted U-shaped members each mounted at one side of the base frame, a track in the form of endless loop around the first shaft and the second shaft, a pulley fastened on one end of the first shaft, a motor assembly having a tubular rod enclosing the first shaft, a pair of conical clutch discs put over a driving shaft of the motor assembly, a belt connecting the pulley to the clutch discs, a speed control mechanism mounted on one of the inverted U-shaped members for regulating speed of the track, and a stand for lifting a front end of the base frame to incline the endless loop to form a slope.